I wouldn't worrie about a week. Feed them before you leave and when you get back feed again, have their tank/racks clean, water full, and they'll be fine.
You don't want to feed them before he leaves. Stop feeding a week prior.
If they poop in the water bowl, your in trouble.
Also, get aspen if you don't have it already for temporary use, so it won't be a mess for them to lay on if they go on newspaper.